This application addresses broad Challenge Area (05) Comparative Effectiveness Research and specific Challenge Topic, 05-MD-101: Social Determinants of Health. In an effort to improve dietary intake and address the high prevalence of obesity among low-income children, the US Department of Agriculture Food and Nutrition Service (USDA-FNS) published an interim rule in the Federal Register revising the food packages in the Special Supplemental Nutrition Program for Women Infants and Children (WIC). WIC provides supplemental food to more than 8 million low-income children women. In response to recommendations from the Institutes of Medicine, the USDA Food and Nutrition Service proposed to align WIC food packages with the Dietary Guidelines for Americans. Among the revisions are changes in the fat content (e.g., reduced fat milk) and the fiber content (e.g., whole grain bread) of foods approved for purchase with WIC vouchers and the addition of a monthly fruit and vegetable voucher. These proposed changes will go into effect in August 2009. We propose to examine the effect of the revised WIC program on consumption of fruits, vegetables, fiber, and reduced-fat foods by low-income children compared to consumption levels under the current WIC program, and we will examine the individual, interpersonal, and community mechanisms that affect dietary intake over the course of the study. The proposed study is important for several reasons. 1) It provides a rare opportunity to evaluate the impact of a national policy shift in food assistance to support healthy eating in low- income families. This national policy shift has the potential to improve healthful eating and may be particularly important in addressing diet-related health disparities, particularly obesity, among low-income individuals. 2) Policymakers are increasingly expressing interest in the use of economic subsidies to improve dietary intake and health outcomes. From a comparative effectiveness perspective, we will be able to assess whether improving access to healthy food changes food intake and ultimately, weight status. 3) The proposed study will build on a pilot project (Chicago WIC Food Environment Survey) we are currently conducting in collaboration with the Illinois Department of Human Services (IDHS), which is responsible for WIC administration in the state, and the Catholic Charities of the Archdiocese of Chicago, the group responsible for WIC distribution in Chicago. The pilot, scheduled for May-July 2009, will provide essential baseline data (0 months) for evaluating the WIC program prior to implementation of the new policy in August 2009. 4) In conjunction with these two agencies, we have the ability to link longitudinal voucher pick-up and voucher redemption data with reported dietary intake, important social contextual variables, and child weight gain trajectory over the first 18 months of the policy (with informed consent). The proposed study will also allow us to create five new positions and retain two current employees that would have been lost due to project completions. The project includes seven FTEs with benefits including a full tuition waiver from the University of Illinois and health insurance benefits for all benefit-eligible employees. This will be particularly appealing to individuals who are seeking further educational opportunities and stable health benefits. Interviewers from the project will gain research skills that will increase their future marketability. The overall purpose of the proposed study is to examine the mechanisms by which economic incentives offered in food assistance program impact dietary intake of children. We are currently collecting pre-policy implementation baseline data (0 months), and the aims of the proposed study are to follow these 300 mother/child dyads, longitudinally, at 6, 12, and 18 months post-policy implementation. Primary Aims 1. To compare fruit and vegetable (FV) intake of children before and at 6, 12, and 18 months following policy implementation. 2. To compare fat and fiber intake of children before and at 6, 12, and 18 months following policy implementation. 3. To examine the individual, interpersonal, and community mechanisms influencing dietary intake before and at 6, 12, and 18 months following policy implementation. Secondary Aims 1. To compare FV intake of mothers before and at 6, 12, and 18 months following policy implementation. 2. To compare fat and fiber intake of mothers before and at 6, 12, and 18 months following policy implementation. Exploratory Aims 1. To compare pick-up and redemption of vouchers before and at 6, 12, and 18 months following policy implementation. 2. To examine weight gain trajectory of 300 preschool children prior to policy implementation through 18 months post policy implementation. In an effort to improve dietary intake and address the high prevalence of obesity among low-income children, the Special Supplemental Nutrition Program for Women Infants and Children (WIC) plans to revise their food packages. The overall purpose of the proposed study is to examine the mechanisms by which economic incentives offered in a large food assistance program impacts dietary intake of children. If the planned economic incentives produce improved dietary intake and altered weight gain trajectory among these high-risk children, this could have profound implications for heath disparities in this population.